The present invention relates, in general, to molding semiconductor packages, and more particularly, to a novel method for molding carrier structures to leads of existing semiconductor packages.
Peripheral carrier structures, or carrier rings had been used by the industry as a protective mechanism for semiconductor packages. Carrier structures prevented damage to leads of a semiconductor package during assembly, test, burn-in, and other phases of semiconductor manufacturing. These carrier structures or carrier rings were strips of plastic or other similar material that encapsulated the ends of the leads of semiconductor packages. Typically the carrier structure was used on high pin count packages that had flat bodies and a rectangular or square shape with leads extending out from all four sides of the package. Generally, carrier rings were molded onto the leads simultaneously with the molding of the plastic body of the package. Attempts to mold carrier rings to semiconductor packages that were previously assembled resulted in bending and distorting the leads of the semiconductor packages. Consequently, semiconductor packages without molded bodies such as ceramic packages, and packages without bodies such as tape automated bonding (TAB) packages, generally used a two piece carrier ring. Typically, an adhesive was used to attach the two piece carrier ring to the leads of the package. During attachment of the two piece ring, some of the leads of the package usually were damaged. Materials for the two piece carrier ring were much more expensive than materials for the molded carrier ring and the process of attaching the two piece carrier ring was also more expensive than the molding process. Consequently, two piece carrier rings were not well accepted by the industry.
Accordingly, it would be desirable to have a method of applying a carrier ring to an assembled semiconductor package that does not damage the leads of the package, and that has a low manufacturing cost.